1. Field of the Invention
This invention relates to a gel-form cleaner which may be used with advantage in flush toilets.
2. Discussion of Related Art
It is known that solid cleaning compositions in block form are used for automatically keeping toilets clean. These cleaning blocks are arranged either in the lavatory bowl or in the cistern. Water flows over the blocks each time the toilet is flushed so that the blocks gradually dissolve and, in doing so, release their cleaning ingredients. Normally, the cleaning blocks also contain fragrance to perfume the surrounding environment or disinfecting agents to optimize hygiene. The described cleaning blocks are applied in suitable containers, in some cases in special refillable containers.
The described cleaning blocks are generally produced by casting, compression, extrusion or granulation processes which involve a high outlay on equipment and which often suffer unwanted losses of perfume through the high temperatures involved (casting/extrusion processes).
Another disadvantage is that the refill units, which are widely used for ecological reasons, can only be employed after the cleaning block has been used up. Selective refilling which would be desirable, for example, to intensify the release of active ingredients or, more particularly, to release more perfume is not possible.
The problem addressed by the present invention was to provide a system which would not have any of the disadvantages described above. It has now surprisingly been found that special gel-form preparations with pseudoplastic properties significantly reduce the outlay on production equipment and can be produced less expensively by a simple process. The problem of individual refillability can also be solved by the pseudoplastic active-substance preparations according to the invention. A special container, which is particularly suitable for the gel-form cleaning compositions according to the invention, is described in DE-A-195 201 45.
The present invention relates to a stable, gel-form and shear-thinning cleaning composition which, in addition to a polysaccharide, contains a C8-22 alkyl polyglycoside as its surfactant system and perfume components, the composition containing a polysaccharide in quantities of 1 to 5% by weight as one component of the surfactant system, a C8-22 alkyl polyglucoside in quantities of 3 to 25% by weight, the perfume component(s) in quantities of 2 to 15% by weight and optionally other ingredients, such as co-surfactants, lime-dissolving agents, dyes, germ inhibitors, pearlescers, stabilizers, cleaning boosters and odor absorbers and having a viscosity in the range from 30,000 to 150,000 mPas (as measured with a Brookfield RVT rotational viscosimeter with a Helipath spindle and TA spindle at 1 r.p.m./23xc2x0 C.).
It has been found that visually attractive, translucent or clear pseudoplastic gel structures, which are as stable as solid rim blocks in suitable containers, can only be obtained with polysaccharides in the described combinations, depending on the types selected with high perfume and APG concentrations.
Other standard gel formers such as, for example, polyacrylic acid (Carbopol), surfactant-thickened systems, MHPC (Natrosol) or sodium- chloride- or electrolyte-thickened surfactant systems do not show adequate gel stability where the high surfactant and perfume levels required are used. These formulations are often not sufficiently pseudoplastic, are diluted by water flowing over them and, on account of their inadequate viscosity behavior, drip uncontrollably into the lavatory bowl despite suitable containers. By contrast, the formulations according to the invention are decidedly pseudoplastic and withstand the water flowing over them to the extent that only small amounts are released and the required stability is obtained. This is because the compositions should also not dissolve too readily in the water penetrating into their containers, otherwise they would be dissolved and therefore exhausted after only a small number of flushes.
In addition, it is important to ensure that, despite the high concentrations of perfume and emulsifier, the gels are guaranteed adequate long-term stability and, for example, do not separate into phases which would not only diminish their visual appeal to the consumer, it would also impair dissolving kinetics and dose control.
Another advantage is that the viscosity of the compositions decreases with increasing shear rate so that they can be packed in containers during the production process and are easy to handle by the consumer during dosing/refilling.
Surprisingly, it has also been found that, under certain conditions in the production process, air bubbles can be introduced into the compositions according to the invention and retain their shape and size over a period of several weeks so that the end product becomes even more attractive to the consumer.
The size of the air bubbles, which can be controlled for example through the stirring rate in the production process and through the viscosity of the compositions, should be neither too large nor too small. In addition, the quantity of air bubbles should only be selected in a preferred range. If, therefore, the presence of air bubbles should be desirable, no more than 30% volume of air should be present, air volumes of 2 to 25% by volume being preferred and air volumes of 5 to 20% by volume being particularly preferred. Particularly preferred embodiments contain air bubbles between 0.1 mm and 20 mm in diameter, air bubbles between 1 mm and 15 mm diameter being most particularly preferred.
However, the viscosity of the compositions according to the invention also enables the air bubbles already introduced in the production process to be removed by brief application of a reduced pressure which may be in a range just below ambient pressure to approaching a vacuum. The duration of the reduced pressure treatment will depend on the strength of the reduced pressure. If a relatively strong reduced pressure is applied, the treatment need not be continued for very long. However, the expert also knows that an excessive reduced pressure can result in unwanted side effects including, for example, the intensified evaporation of readily volatile perfume components and, in some cases, problems affecting the stirrability of the system. Although the compositions according to the invention can be degassed by treatment in a centrifuge or by ultrarapid stirring, such treatments are not preferred.
This is because, if possible, the compositions according to the invention should not be exposed to excessive shear forces during or after the production process because otherwise the properties according to the invention would often be lost in the short to medium term and could only be recovered after long waiting times.
The formulations according to the invention may be produced in various ways and in various batch sizes up to, and including, several tonnes.
Normally, water is introduced into a commercially available mixer, for example a Beco-Mix, and the dye is stirred in. The xanthan gum preferably used as the polysaccharide is separately suspended with solvent, preferably ethanol, and the required perfume oil. The suspension is then added and the whole is stirred at low speed, for example at 30 r.p.m.
Investigations have shown that, after all the components have been added, a time of a few minutes to a few hours is required to reach the consistency according to the invention. In the present case, the surfactant (alkyl polyglycoside) was slowly added after 30 minutes. The other components are then added. If a bubble-free gel is to be guaranteed, the mixture has to be placed under a reduced pressure or under a vacuum, as described above, in a suitable container in dependence upon its viscosity, but generally for a short time, for example 15 minutes.
However, other procedures may be adopted. This is advisable, for example, where disinfectants are to be included. In this case, water is normally introduced into a commercially available mixer, for example a Beco-Mix, and the xanthan gum used is then stirred in. The suspension is then added and the whole is stirred at low speed, for example at 30 r.p.m., before the surfactant mixture (alkyl polyglycol/fatty alcohol ether sulfate) is slowly added after 30 minutes. The dye is then added before a solution of the perfume in ethanol is introduced. The disinfectant, preferably selected from the group of isothiazolines, benzoates or salicylic acid or salicylates, is added next. In this case, the composition can be packed in commercially available measuring bottles, for example in a rotary bottle filling machine.
Particular care has to be taken when substances are added to the prepared and swollen water-containing xanthan gel to allow the structure according to the invention to form. If these substances are added too quickly, phase separation problems can arise. In addition, no surfactant should be present during the preparation of the xanthan gel component because it would prevent gel formation. Accordingly, it is very much preferred to add the surfactant components after formation of the gel.
Viscosity may be measured by any of the methods normally used. Brookfield viscosimeters which have a spindle specially designed for gels were used in the present case. The viscosities according to the invention were measured with this Helipath spindle.
In one basic formulation, the compositions according to the invention may contain the following components:
1.0-5.0% by weight of polysaccharide
3.0-25.0% by weight of C8-22 alkyl polyglycoside
0-15.0% by weight of co-surfactants (FAS, FAEOS)
0-5.0% by weight of citric acid
0-5.0% by weight of complexing agent
2 to 15% by weight, preferably 2 to 12% by weight and more preferably 3 to 8% by weight of perfume
up to 5.0% by weight and preferably from 0.01 to 4% by weight of solvent, for example ethanol
0-1.0% by weight of preservative
0-10.0% by weight of dye
0-5.0% by weight and preferably 0.01 to 3% by weight of germ inhibitor.
In the context of the present invention, a polysaccharide is understood, for example, to be a xanthan gum or a guar gum or a mixture of polysaccharides. Xanthan is formed from a chain with xcex2-1,4-linked glucose (cellulose) with side chains. The structure of the sub-groups consists of glucose, mannose, glucuronic acid, acetate and pyruvate. Xanthan is produced by Xanthonomas campestris under aerobic conditions with a molecular weight of 2-15xc3x97106. Xanthan is produced inter alia in bath cultures and, after destruction of the culture and precipitation with propanol, is dried and ground. Other suitable methods are also described in the literature. The polysaccharide, particularly xanthan gum, is present in the compositions in quantities of 1 to 4% by weight, preferably 1.5 to 3.5% by weight and more preferably 1.8 to 3% by weight.
Alkyl polyglycosides are surfactants which may be obtained by reacting sugars and alcohols using the relevant methods of preparative organic chemistry. A mixture of monoalkylated, oligomeric or polymeric sugars is obtained according to the particular method of production used. Preferred alkyl polyglycosides are alkyl polyglucosides. In a particularly preferred embodiment, the alcohol is a long-chain fatty alcohol with alkyl chain lengths of C8 to C22, preferably from C8 to C16 and more preferably from C8 to C12 or a mixture of long-chain fatty alcohols. The degree of oligomerization of the sugars which is a calculated quantity, i.e. is generally not a whole number, is between 1 and 10, preferably between 1.1 and 5, more preferably between 1.2 and 3 and most preferably between 1.3 and 2.5. The compositions contain C8-22 alkyl polyglycosides in quantities of preferably 4 to 20% by weight, more preferably 5 to 17% by weight and most preferably 5 to 15% by weight. Quantities of up to 12% by weight can also be of advantage.
According to the invention, anionic co-surfactants include aliphatic sulfates, such as fatty alcohol sulfates, fatty alcohol ether sulfates, dialkyl ether sulfates, monoglyceride sulfates, and aliphatic sulfonates, such as alkane sulfonates, olefin sulfonates, ether sulfonates, n-alkyl ether sulfonates, ester sulfonates and lignin sulfonates. Other anionic cosurfactants which may be used in accordance with the invention, but are not preferred, include fatty acid cyanamides, sulfosuccinic acid esters, fatty acid isethionates, acylaminoalkane sulfonates (fatty acid taurides), fatty acid sarcosinates, ether carboxylic acids and alkyl (ether)phosphates. Fatty alcohol sulfates and fatty alcohol ether sulfates are preferably used. Hitherto, less favorable results were obtained with alkyl benzenesulfonates.
In one preferred embodiment of the invention, the ratio by weight of alkyl polyglycoside to co-surfactants, more particularly to fatty alcohol ether sulfates and/or fatty alcohol sulfate, is at least 1:1, ratios of 50:1 to 1:1, preferably from 10:1 to 1.5:1 and more preferably from 5:1 to 1.8:1 being particularly advantageous.
However, nonionic co-surfactants may also be used. Nonionic surfactants in the context of the present invention include alkoxylated alcohols, such as polyglycol ethers, fatty alcohol polyglycol ethers, alkylphenol polyglycol ethers, end-capped polyglycol ethers, mixed ethers and hydroxy mixed ethers and fatty acid polyglycol esters. Ethylene oxide, propylene oxide, block polymers and fatty acid alkanolamides and fatty acid polyglycol ethers may also be used.
Alkoxylated alcohols are generally understood to be the reaction products of alkylene oxide, preferably ethylene oxide, with alcohols. Relatively long-chain alcohols are preferred for the purposes of the present invention. Depending on the reaction conditions, a complex mixture of addition products with different degrees of ethoxylation is generally formed from n mol of ethylene oxide and 1 mol of alcohol. Another embodiment is characterized by the use of mixtures of alkylene oxides, preferably a mixture of ethylene oxide and propylene oxide. If desired, xe2x80x9ccappedxe2x80x9d alcohol ethoxylates, which may also be used for the purposes of the invention, can also be obtained by etherification with short-chain alkyl groups, preferably butyl groups, in a concluding step. According to the invention, highly ethoxylated fatty alcohols or mixtures thereof with end-capped fatty alcohol ethoxylates are most particularly preferred.
The described formulations may advantageously contain inorganic or organic acids, such as citric acid, acetic acid, lactic acid or water-soluble salts thereof, in a quantity of 1 to 12% by weight as the lime-dissolving agent. Contents of 2 to 5% by weight are particularly preferred.
The compositions according to the invention preferably contain dye either for coloring the product or for coloring the liquid circulating around the container. In a preferred embodiment, the content of water-soluble dyes is below 1% by weight and is intended to improve the appearance of the product. If an additional color signal is required during flushing, the content of water-soluble dyes may be increased to 5% by weight. The content of water-soluble dye is preferably up to 3% by weight, more preferably up to 2% by weight and most preferably up to 1% by weight.
Although the gels according to the invention already have an excellent cleaning effect without this component, the hygienic effect can be enhanced by the addition of germ inhibitors. The quantity of germ inhibitor used is governed to a large extent by the effectiveness of the particular compound and may be as much as 5% by weight. A quantity of at least 0.01% by weight is preferably incorporated in the gels, quantities of 0.01% by weight to 3% by weight being particularly preferred. Isothiazoline mixtures, sodium benzoate or salicylic acid and salicylates are particularly suitable. Other preferred quantities are from 0.01 to 2% by weight and more preferably from 0.01 to 1% by weight.
Suitable solubilizers, for example for dyes and perfume oils, include for example alkanolamines, polyols, such as ethylene glycol, representatives of the lower alcohols, such as propylene glycol, glycerol and other monohydric and polyhydric alcohols and also alkyl benzenesulfonates with 1 to 3 carbon atoms in the alkyl moiety. The group of lower alcohols is particularly preferred, ethanol being most particularly preferred. Preferred quantities are up to 5% by weight, more particularly between 0.01 and 4% by weight, advantageously between 0.1 and 4% by weight and, in a most particularly preferred embodiment, between 0.5 and 3% by weight.
Conventional thickeners, which could be used if required, include urea, sodium chloride, sodium sulfate, magnesium sulfate, ammonium chloride and magnesium chloride and combinations thereof. However, the use of these additional thickeners is not preferred.
The cleaning compositions according to the invention may optionally contain water-soluble and water-insoluble builders. Water-soluble builders are preferred because they are generally not as prone to form insoluble residues on hard surfaces. Conventional builders or complexing agents which may be present in accordance with the invention include low molecular weight polycarboxylic acids and salts thereof, homopolymeric and copolymeric polycarboxylic acids and salts thereof, citric acid and salts thereof, carbonates, phosphates and silicates. Water-insoluble builders include zeolites, which may also be used, and mixtures of the builders mentioned above. The group of citrates is particularly preferred. The compositions according to the invention contain builders or complexing agents in quantities of up 10% by weight, preferably from 0.1 to 8% by weight, more preferably from 1 to 6% by weight and most preferably from 2 to 5% by weight.